1. Technical Field of the Invention
The present invention relates to a liquid-crystal display device, in particular to a liquid-crystal display device, employing an in-plane switching-mode, in which an electric field is applied to the horizontally-aligned nematic liquid crystal laterally.
2. Related Art
An in-plane switching (IPS)-mode liquid-crystal display device has been proposed in which a lateral electric field is applied to the liquid crystal. Recently, the liquid-crystal display device employing the mode has been developed for use for TVs, and with that, the panel brightness thereof has become greatly increased. Accordingly, even slight light leakage in diagonal oblique directions in the black state, which has heretofore been almost disregarded in IPS-mode devices, has become considered a cause of deterioration of display image quality in the devices.
For improving the color expression of IPS-mode display devices and for improving the viewing angle characteristics thereof in the black state, some methods of disposing an optical compensatory material having birefringent characteristics between the liquid-crystal layer and the polarizer have been tried. And some methods of making a protective film of the polarizer capable of functioning as an optical compensation have also been tried for example, see JPA Nos. hei 9-80424, hei 10-54982, hei 11-202323, hei 9-292522, hei 11-133408, hei 11-305217, hei 10-307291 and 2006-227606.